DESCRIPTION: Trypanosoma cruzi causes Chagas'disease, which affects over 11 million people in Latin America. Of those infected, about 5 million will develop severe cardiac and/or digestive disorders. Annually, up to 50,000 people may die and many others will become physically disabled. Recently, Chagas'disease became a public health concern in the United States, owing to the rising number of chronically infected migrants. Currently, there is only one partially effective drug commercially available;there is no human vaccine. Our long-term goal is to understand the molecular events involved in the interaction of T. cruzi with host cells, aiming at the establishment of rational bases for the development of more effective therapies Our hypothesis is that alphaGal-containing vesicles shed by the infective trypomastigote stage of T. cruzi (TcalphaGalVes) contain the major parasite virulence factors, responsible for both the recurrent cell invasion and escaping from host immunity. We also propose that TcalphaGalVes might be accountable for the marked inflammatory process observed in the chronic phase of the disease. Our hypothesis is based on the observations that TcalphaGalVes greatly enhance the host cell invasion by engaging Toll-like receptor 2 (TLR2). Our specific aims are: Specific Aim # 1: To determine the molecular composition of TcalphaGalVes. We will perform a detailed analysis of proteins and post-translational modifications (PTMs), such as glycosylation, glycosylphosphatidylinositol (GPI) anchoring, and phosphorylation. Specific Aim # 2: To define how TcalphaGalVes interact with host cell receptors and enhance cell invasion. We intend to identify and characterize the host alphaGal-binding protein, study its interaction with TLR2, and learn how this leads to the increase of parasite entry into the cell. Electron and confocal microscopy analyses of the early interactions between TcalphaGalVes and host cells will be carried out. We believe that the successful achievement of these specific aims will greatly advance our knowledge of the fine molecular mechanisms used by T. cruzi to invade host cells and escape from the host anti-parasitic immunity. Our ultimate goal is to establish a rational basis for the development of more effective therapies against this deadly pathogen.